Normally the cellular OFDMA system with a frequency reuse factor 1 such as IEEE802.16e may confront degradation in transmission ratio due to poor carrier-to-interference and noise ratio (CINR) near cell peripheries and therefore may restrict coverage performance due to service outage. In order to solve such problems, IEEE 802.16j TG in the IEEE 802.16 Wireless MAN standardization group is pushing ahead with the standardization of a multi-hop relay (MR) system based on cellular OFDMA. The MR system is composed of a repeater, i.e., a relay station (RS), which supports a radio relay function for connection of a mobile station (MS), and a base station (BS) which is connected with the MS or RS through a radio link and supports a radio relay function. The MS may directly communicate the MR-BS or may be connected with the MR-BS through two-hop using a single RS or multi-hop using several RSs. This system simultaneously offers an access zone of the MS and a relay zone between the RS and the MR-BS by means of time division of a single radio frequency channel, thus requiring no additional wired link for a relay link. Namely, the multi-hop relay system not only can increase yield by improving CINR performance of the adjoining MS through the RS, but also may cover a service outage area or expand cell coverage by installing the RS in a shaded zone. Accordingly, the multi-hop relay system may divide the entire cell into a number of small coverage regions through multi-hop RSs, and may realize an increase of system capacity through reuse of the same radio resources by all RSs.
Meanwhile, the MS accesses a specific server or other MS through the BS and then establishes downlink and uplink channels with the BS in order to use a certain service. Namely, the MS forms a downlink channel with the BS to receive data from a specific server or other MS, and also forms an uplink channel with the BS to upload or transmit data to a specific server or other MS. Particularly, the MS requests uplink bandwidth for data transmission to the BS and, for such a request, creates a separate bandwidth request message to be transmitted to the BS.
By the way, if there is any RS between the MS and the BS during a bandwidth request process of the MS, the MS sends a bandwidth request to the RS, and then the RS sends a message corresponding to the bandwidth request to the BS. So, if the MS uses several services or if several MSs use several services, the above messages for bandwidth requests are increased and hence this may incur an increase of message transmission load. Therefore, a method and system for a more effective bandwidth request are needed.